Annotation of src/usr.bin/ssh/channels.c, Revision 1.26
1.1 deraadt 1: /*
1.26 ! deraadt 2: *
! 3: * channels.c
! 4: *
! 5: * Author: Tatu Ylonen <ylo@cs.hut.fi>
! 6: *
! 7: * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
! 8: * All rights reserved
! 9: *
! 10: * Created: Fri Mar 24 16:35:24 1995 ylo
! 11: *
! 12: * This file contains functions for generic socket connection forwarding.
! 13: * There is also code for initiating connection forwarding for X11 connections,
! 14: * arbitrary tcp/ip connections, and the authentication agent connection.
! 15: *
! 16: */
1.1 deraadt 17:
18: #include "includes.h"
1.26 ! deraadt 19: RCSID("$Id: channels.c,v 1.25 1999/11/23 22:25:53 markus Exp $");
1.1 deraadt 20:
21: #include "ssh.h"
22: #include "packet.h"
23: #include "xmalloc.h"
24: #include "buffer.h"
25: #include "authfd.h"
26: #include "uidswap.h"
1.20 markus 27: #include "readconf.h"
1.3 deraadt 28: #include "servconf.h"
1.1 deraadt 29:
1.14 markus 30: #include "channels.h"
31: #include "nchan.h"
32: #include "compat.h"
33:
1.1 deraadt 34: /* Maximum number of fake X11 displays to try. */
35: #define MAX_DISPLAYS 1000
36:
1.12 markus 37: /* Max len of agent socket */
38: #define MAX_SOCKET_NAME 100
39:
1.1 deraadt 40: /* Pointer to an array containing all allocated channels. The array is
41: dynamically extended as needed. */
42: static Channel *channels = NULL;
43:
44: /* Size of the channel array. All slots of the array must always be
45: initialized (at least the type field); unused slots are marked with
46: type SSH_CHANNEL_FREE. */
47: static int channels_alloc = 0;
48:
49: /* Maximum file descriptor value used in any of the channels. This is updated
50: in channel_allocate. */
51: static int channel_max_fd_value = 0;
52:
1.12 markus 53: /* Name and directory of socket for authentication agent forwarding. */
1.1 deraadt 54: static char *channel_forwarded_auth_socket_name = NULL;
1.25 markus 55: static char *channel_forwarded_auth_socket_dir = NULL;
1.1 deraadt 56:
57: /* Saved X11 authentication protocol name. */
58: char *x11_saved_proto = NULL;
59:
60: /* Saved X11 authentication data. This is the real data. */
61: char *x11_saved_data = NULL;
62: unsigned int x11_saved_data_len = 0;
63:
64: /* Fake X11 authentication data. This is what the server will be sending
65: us; we should replace any occurrences of this by the real data. */
66: char *x11_fake_data = NULL;
67: unsigned int x11_fake_data_len;
68:
69: /* Data structure for storing which hosts are permitted for forward requests.
70: The local sides of any remote forwards are stored in this array to prevent
71: a corrupt remote server from accessing arbitrary TCP/IP ports on our
72: local network (which might be behind a firewall). */
1.25 markus 73: typedef struct {
74: char *host; /* Host name. */
75: int port; /* Port number. */
1.1 deraadt 76: } ForwardPermission;
77:
78: /* List of all permitted host/port pairs to connect. */
79: static ForwardPermission permitted_opens[SSH_MAX_FORWARDS_PER_DIRECTION];
80: /* Number of permitted host/port pairs in the array. */
81: static int num_permitted_opens = 0;
82: /* If this is true, all opens are permitted. This is the case on the
83: server on which we have to trust the client anyway, and the user could
84: do anything after logging in anyway. */
85: static int all_opens_permitted = 0;
86:
87: /* This is set to true if both sides support SSH_PROTOFLAG_HOST_IN_FWD_OPEN. */
88: static int have_hostname_in_open = 0;
89:
90: /* Sets specific protocol options. */
91:
1.25 markus 92: void
93: channel_set_options(int hostname_in_open)
1.1 deraadt 94: {
1.25 markus 95: have_hostname_in_open = hostname_in_open;
1.1 deraadt 96: }
97:
98: /* Permits opening to any host/port in SSH_MSG_PORT_OPEN. This is usually
99: called by the server, because the user could connect to any port anyway,
100: and the server has no way to know but to trust the client anyway. */
101:
1.25 markus 102: void
103: channel_permit_all_opens()
1.1 deraadt 104: {
1.25 markus 105: all_opens_permitted = 1;
1.1 deraadt 106: }
107:
1.25 markus 108: /* Allocate a new channel object and set its type and socket.
1.1 deraadt 109: This will cause remote_name to be freed. */
110:
1.25 markus 111: int
112: channel_allocate(int type, int sock, char *remote_name)
1.1 deraadt 113: {
1.25 markus 114: int i, found;
115: Channel *c;
1.1 deraadt 116:
1.25 markus 117: /* Update the maximum file descriptor value. */
118: if (sock > channel_max_fd_value)
119: channel_max_fd_value = sock;
120:
121: /* Do initial allocation if this is the first call. */
122: if (channels_alloc == 0) {
123: channels_alloc = 10;
124: channels = xmalloc(channels_alloc * sizeof(Channel));
125: for (i = 0; i < channels_alloc; i++)
126: channels[i].type = SSH_CHANNEL_FREE;
127:
128: /* Kludge: arrange a call to channel_stop_listening if we
129: terminate with fatal(). */
130: fatal_add_cleanup((void (*) (void *)) channel_stop_listening, NULL);
131: }
132: /* Try to find a free slot where to put the new channel. */
133: for (found = -1, i = 0; i < channels_alloc; i++)
134: if (channels[i].type == SSH_CHANNEL_FREE) {
135: /* Found a free slot. */
136: found = i;
137: break;
138: }
139: if (found == -1) {
140: /* There are no free slots. Take last+1 slot and expand
141: the array. */
142: found = channels_alloc;
143: channels_alloc += 10;
144: debug("channel: expanding %d", channels_alloc);
145: channels = xrealloc(channels, channels_alloc * sizeof(Channel));
146: for (i = found; i < channels_alloc; i++)
147: channels[i].type = SSH_CHANNEL_FREE;
148: }
149: /* Initialize and return new channel number. */
150: c = &channels[found];
151: buffer_init(&c->input);
152: buffer_init(&c->output);
153: chan_init_iostates(c);
154: c->self = found;
155: c->type = type;
156: c->sock = sock;
157: c->remote_id = -1;
158: c->remote_name = remote_name;
159: debug("channel %d: new [%s]", found, remote_name);
160: return found;
1.1 deraadt 161: }
162:
163: /* Free the channel and close its socket. */
164:
1.25 markus 165: void
166: channel_free(int channel)
1.1 deraadt 167: {
1.25 markus 168: if (channel < 0 || channel >= channels_alloc ||
169: channels[channel].type == SSH_CHANNEL_FREE)
170: packet_disconnect("channel free: bad local channel %d", channel);
171:
172: if (compat13)
173: shutdown(channels[channel].sock, SHUT_RDWR);
174: close(channels[channel].sock);
175: buffer_free(&channels[channel].input);
176: buffer_free(&channels[channel].output);
177: channels[channel].type = SSH_CHANNEL_FREE;
178: if (channels[channel].remote_name) {
179: xfree(channels[channel].remote_name);
180: channels[channel].remote_name = NULL;
181: }
1.1 deraadt 182: }
183:
184: /* This is called just before select() to add any bits relevant to
185: channels in the select bitmasks. */
186:
1.25 markus 187: void
188: channel_prepare_select(fd_set * readset, fd_set * writeset)
1.1 deraadt 189: {
1.25 markus 190: int i;
191: Channel *ch;
192: unsigned char *ucp;
193: unsigned int proto_len, data_len;
194:
195: for (i = 0; i < channels_alloc; i++) {
196: ch = &channels[i];
197: redo:
198: switch (ch->type) {
199: case SSH_CHANNEL_X11_LISTENER:
200: case SSH_CHANNEL_PORT_LISTENER:
201: case SSH_CHANNEL_AUTH_SOCKET:
202: FD_SET(ch->sock, readset);
203: break;
204:
205: case SSH_CHANNEL_OPEN:
206: if (compat13) {
207: if (buffer_len(&ch->input) < packet_get_maxsize())
208: FD_SET(ch->sock, readset);
209: if (buffer_len(&ch->output) > 0)
210: FD_SET(ch->sock, writeset);
211: break;
212: }
213: /* test whether sockets are 'alive' for read/write */
214: if (ch->istate == CHAN_INPUT_OPEN)
215: if (buffer_len(&ch->input) < packet_get_maxsize())
216: FD_SET(ch->sock, readset);
217: if (ch->ostate == CHAN_OUTPUT_OPEN ||
218: ch->ostate == CHAN_OUTPUT_WAIT_DRAIN) {
219: if (buffer_len(&ch->output) > 0) {
220: FD_SET(ch->sock, writeset);
221: } else if (ch->ostate == CHAN_OUTPUT_WAIT_DRAIN) {
222: chan_obuf_empty(ch);
223: }
224: }
225: break;
226:
227: case SSH_CHANNEL_INPUT_DRAINING:
228: if (!compat13)
229: fatal("cannot happen: IN_DRAIN");
230: if (buffer_len(&ch->input) == 0) {
231: packet_start(SSH_MSG_CHANNEL_CLOSE);
232: packet_put_int(ch->remote_id);
233: packet_send();
234: ch->type = SSH_CHANNEL_CLOSED;
235: debug("Closing channel %d after input drain.", i);
236: break;
237: }
238: break;
239:
240: case SSH_CHANNEL_OUTPUT_DRAINING:
241: if (!compat13)
242: fatal("cannot happen: OUT_DRAIN");
243: if (buffer_len(&ch->output) == 0) {
244: channel_free(i);
245: break;
246: }
247: FD_SET(ch->sock, writeset);
248: break;
249:
250: case SSH_CHANNEL_X11_OPEN:
251: /* This is a special state for X11 authentication
252: spoofing. An opened X11 connection (when
253: authentication spoofing is being done) remains
254: in this state until the first packet has been
255: completely read. The authentication data in
256: that packet is then substituted by the real
257: data if it matches the fake data, and the
258: channel is put into normal mode. */
259:
260: /* Check if the fixed size part of the packet is in buffer. */
261: if (buffer_len(&ch->output) < 12)
262: break;
263:
264: /* Parse the lengths of variable-length fields. */
265: ucp = (unsigned char *) buffer_ptr(&ch->output);
266: if (ucp[0] == 0x42) { /* Byte order MSB first. */
267: proto_len = 256 * ucp[6] + ucp[7];
268: data_len = 256 * ucp[8] + ucp[9];
269: } else if (ucp[0] == 0x6c) { /* Byte order LSB first. */
270: proto_len = ucp[6] + 256 * ucp[7];
271: data_len = ucp[8] + 256 * ucp[9];
272: } else {
273: debug("Initial X11 packet contains bad byte order byte: 0x%x",
274: ucp[0]);
275: ch->type = SSH_CHANNEL_OPEN;
276: goto reject;
277: }
278:
279: /* Check if the whole packet is in buffer. */
280: if (buffer_len(&ch->output) <
281: 12 + ((proto_len + 3) & ~3) + ((data_len + 3) & ~3))
282: break;
283:
284: /* Check if authentication protocol matches. */
285: if (proto_len != strlen(x11_saved_proto) ||
286: memcmp(ucp + 12, x11_saved_proto, proto_len) != 0) {
287: debug("X11 connection uses different authentication protocol.");
288: ch->type = SSH_CHANNEL_OPEN;
289: goto reject;
290: }
291: /* Check if authentication data matches our fake data. */
292: if (data_len != x11_fake_data_len ||
293: memcmp(ucp + 12 + ((proto_len + 3) & ~3),
294: x11_fake_data, x11_fake_data_len) != 0) {
295: debug("X11 auth data does not match fake data.");
296: ch->type = SSH_CHANNEL_OPEN;
297: goto reject;
298: }
299: /* Check fake data length */
300: if (x11_fake_data_len != x11_saved_data_len) {
301: error("X11 fake_data_len %d != saved_data_len %d",
302: x11_fake_data_len, x11_saved_data_len);
303: ch->type = SSH_CHANNEL_OPEN;
304: goto reject;
305: }
306: /* Received authentication protocol and data match
307: our fake data. Substitute the fake data with
308: real data. */
309: memcpy(ucp + 12 + ((proto_len + 3) & ~3),
310: x11_saved_data, x11_saved_data_len);
311:
312: /* Start normal processing for the channel. */
313: ch->type = SSH_CHANNEL_OPEN;
314: goto redo;
315:
1.1 deraadt 316: reject:
1.25 markus 317: /* We have received an X11 connection that has bad
318: authentication information. */
319: log("X11 connection rejected because of wrong authentication.\r\n");
320: buffer_clear(&ch->input);
321: buffer_clear(&ch->output);
322: if (compat13) {
323: close(ch->sock);
324: ch->sock = -1;
325: ch->type = SSH_CHANNEL_CLOSED;
326: packet_start(SSH_MSG_CHANNEL_CLOSE);
327: packet_put_int(ch->remote_id);
328: packet_send();
329: } else {
330: debug("X11 rejected %d i%d/o%d", ch->self, ch->istate, ch->ostate);
331: chan_read_failed(ch);
332: chan_write_failed(ch);
333: debug("X11 rejected %d i%d/o%d", ch->self, ch->istate, ch->ostate);
334: }
335: break;
336:
337: case SSH_CHANNEL_FREE:
338: default:
339: continue;
340: }
1.1 deraadt 341: }
342: }
343:
344: /* After select, perform any appropriate operations for channels which
345: have events pending. */
346:
1.25 markus 347: void
348: channel_after_select(fd_set * readset, fd_set * writeset)
1.1 deraadt 349: {
1.25 markus 350: struct sockaddr addr;
351: int addrlen, newsock, i, newch, len;
352: Channel *ch;
353: char buf[16384], *remote_hostname;
354:
355: /* Loop over all channels... */
356: for (i = 0; i < channels_alloc; i++) {
357: ch = &channels[i];
358: switch (ch->type) {
359: case SSH_CHANNEL_X11_LISTENER:
360: /* This is our fake X11 server socket. */
361: if (FD_ISSET(ch->sock, readset)) {
362: debug("X11 connection requested.");
363: addrlen = sizeof(addr);
364: newsock = accept(ch->sock, &addr, &addrlen);
365: if (newsock < 0) {
366: error("accept: %.100s", strerror(errno));
367: break;
368: }
369: remote_hostname = get_remote_hostname(newsock);
370: snprintf(buf, sizeof buf, "X11 connection from %.200s port %d",
371: remote_hostname, get_peer_port(newsock));
372: xfree(remote_hostname);
373: newch = channel_allocate(SSH_CHANNEL_OPENING, newsock,
374: xstrdup(buf));
375: packet_start(SSH_SMSG_X11_OPEN);
376: packet_put_int(newch);
377: if (have_hostname_in_open)
378: packet_put_string(buf, strlen(buf));
379: packet_send();
380: }
381: break;
382:
383: case SSH_CHANNEL_PORT_LISTENER:
384: /* This socket is listening for connections to a
385: forwarded TCP/IP port. */
386: if (FD_ISSET(ch->sock, readset)) {
387: debug("Connection to port %d forwarding to %.100s:%d requested.",
388: ch->listening_port, ch->path, ch->host_port);
389: addrlen = sizeof(addr);
390: newsock = accept(ch->sock, &addr, &addrlen);
391: if (newsock < 0) {
392: error("accept: %.100s", strerror(errno));
393: break;
394: }
395: remote_hostname = get_remote_hostname(newsock);
396: snprintf(buf, sizeof buf, "listen port %d:%.100s:%d, connect from %.200s:%d",
397: ch->listening_port, ch->path, ch->host_port,
398: remote_hostname, get_peer_port(newsock));
399: xfree(remote_hostname);
400: newch = channel_allocate(SSH_CHANNEL_OPENING, newsock,
401: xstrdup(buf));
402: packet_start(SSH_MSG_PORT_OPEN);
403: packet_put_int(newch);
404: packet_put_string(ch->path, strlen(ch->path));
405: packet_put_int(ch->host_port);
406: if (have_hostname_in_open)
407: packet_put_string(buf, strlen(buf));
408: packet_send();
409: }
410: break;
411:
412: case SSH_CHANNEL_AUTH_SOCKET:
413: /* This is the authentication agent socket
414: listening for connections from clients. */
415: if (FD_ISSET(ch->sock, readset)) {
416: int nchan;
417: len = sizeof(addr);
418: newsock = accept(ch->sock, &addr, &len);
419: if (newsock < 0) {
420: error("accept from auth socket: %.100s", strerror(errno));
421: break;
422: }
423: nchan = channel_allocate(SSH_CHANNEL_OPENING, newsock,
424: xstrdup("accepted auth socket"));
425: packet_start(SSH_SMSG_AGENT_OPEN);
426: packet_put_int(nchan);
427: packet_send();
428: }
429: break;
430:
431: case SSH_CHANNEL_OPEN:
432: /* This is an open two-way communication channel.
433: It is not of interest to us at this point what
434: kind of data is being transmitted. */
435:
436: /* Read available incoming data and append it to
437: buffer; shutdown socket, if read or write
438: failes */
439: if (FD_ISSET(ch->sock, readset)) {
440: len = read(ch->sock, buf, sizeof(buf));
441: if (len <= 0) {
442: if (compat13) {
443: buffer_consume(&ch->output, buffer_len(&ch->output));
444: ch->type = SSH_CHANNEL_INPUT_DRAINING;
445: debug("Channel %d status set to input draining.", i);
446: } else {
447: chan_read_failed(ch);
448: }
449: break;
450: }
451: buffer_append(&ch->input, buf, len);
452: }
453: /* Send buffered output data to the socket. */
454: if (FD_ISSET(ch->sock, writeset) && buffer_len(&ch->output) > 0) {
455: len = write(ch->sock, buffer_ptr(&ch->output),
456: buffer_len(&ch->output));
457: if (len <= 0) {
458: if (compat13) {
459: buffer_consume(&ch->output, buffer_len(&ch->output));
460: debug("Channel %d status set to input draining.", i);
461: ch->type = SSH_CHANNEL_INPUT_DRAINING;
462: } else {
463: chan_write_failed(ch);
464: }
465: break;
466: }
467: buffer_consume(&ch->output, len);
468: }
469: break;
470:
471: case SSH_CHANNEL_OUTPUT_DRAINING:
472: if (!compat13)
473: fatal("cannot happen: OUT_DRAIN");
474: /* Send buffered output data to the socket. */
475: if (FD_ISSET(ch->sock, writeset) && buffer_len(&ch->output) > 0) {
476: len = write(ch->sock, buffer_ptr(&ch->output),
477: buffer_len(&ch->output));
478: if (len <= 0)
479: buffer_consume(&ch->output, buffer_len(&ch->output));
480: else
481: buffer_consume(&ch->output, len);
482: }
483: break;
484:
485: case SSH_CHANNEL_X11_OPEN:
486: case SSH_CHANNEL_FREE:
487: default:
488: continue;
1.1 deraadt 489: }
490: }
491: }
492:
493: /* If there is data to send to the connection, send some of it now. */
494:
1.25 markus 495: void
496: channel_output_poll()
1.1 deraadt 497: {
1.25 markus 498: int len, i;
499: Channel *ch;
1.1 deraadt 500:
1.25 markus 501: for (i = 0; i < channels_alloc; i++) {
502: ch = &channels[i];
503: /* We are only interested in channels that can have
504: buffered incoming data. */
505: if (ch->type != SSH_CHANNEL_OPEN &&
506: ch->type != SSH_CHANNEL_INPUT_DRAINING)
507: continue;
508:
509: /* Get the amount of buffered data for this channel. */
510: len = buffer_len(&ch->input);
511: if (len > 0) {
512: /* Send some data for the other side over the
513: secure connection. */
514: if (packet_is_interactive()) {
515: if (len > 1024)
516: len = 512;
517: } else {
518: /* Keep the packets at reasonable size. */
519: if (len > 16384)
520: len = 16384;
521: }
522: packet_start(SSH_MSG_CHANNEL_DATA);
523: packet_put_int(ch->remote_id);
524: packet_put_string(buffer_ptr(&ch->input), len);
525: packet_send();
526: buffer_consume(&ch->input, len);
527: } else if (ch->istate == CHAN_INPUT_WAIT_DRAIN) {
528: if (compat13)
529: fatal("cannot happen: istate == INPUT_WAIT_DRAIN for proto 1.3");
530: /* input-buffer is empty and read-socket shutdown:
531: tell peer, that we will not send more data:
532: send IEOF */
533: chan_ibuf_empty(ch);
534: }
535: }
1.1 deraadt 536: }
537:
538: /* This is called when a packet of type CHANNEL_DATA has just been received.
539: The message type has already been consumed, but channel number and data
540: is still there. */
541:
1.25 markus 542: void
543: channel_input_data(int payload_len)
1.1 deraadt 544: {
1.25 markus 545: int channel;
546: char *data;
547: unsigned int data_len;
548:
549: /* Get the channel number and verify it. */
550: channel = packet_get_int();
551: if (channel < 0 || channel >= channels_alloc ||
552: channels[channel].type == SSH_CHANNEL_FREE)
553: packet_disconnect("Received data for nonexistent channel %d.", channel);
554:
555: /* Ignore any data for non-open channels (might happen on close) */
556: if (channels[channel].type != SSH_CHANNEL_OPEN &&
557: channels[channel].type != SSH_CHANNEL_X11_OPEN)
558: return;
559:
560: /* Get the data. */
561: data = packet_get_string(&data_len);
562: packet_integrity_check(payload_len, 4 + 4 + data_len, SSH_MSG_CHANNEL_DATA);
563: buffer_append(&channels[channel].output, data, data_len);
564: xfree(data);
1.1 deraadt 565: }
566:
567: /* Returns true if no channel has too much buffered data, and false if
568: one or more channel is overfull. */
569:
1.25 markus 570: int
571: channel_not_very_much_buffered_data()
1.1 deraadt 572: {
1.25 markus 573: unsigned int i;
574: Channel *ch;
575:
576: for (i = 0; i < channels_alloc; i++) {
577: ch = &channels[i];
578: switch (ch->type) {
579: case SSH_CHANNEL_X11_LISTENER:
580: case SSH_CHANNEL_PORT_LISTENER:
581: case SSH_CHANNEL_AUTH_SOCKET:
582: continue;
583: case SSH_CHANNEL_OPEN:
584: if (buffer_len(&ch->input) > packet_get_maxsize())
585: return 0;
586: if (buffer_len(&ch->output) > packet_get_maxsize())
587: return 0;
588: continue;
589: case SSH_CHANNEL_INPUT_DRAINING:
590: case SSH_CHANNEL_OUTPUT_DRAINING:
591: case SSH_CHANNEL_X11_OPEN:
592: case SSH_CHANNEL_FREE:
593: default:
594: continue;
595: }
1.1 deraadt 596: }
1.25 markus 597: return 1;
1.1 deraadt 598: }
599:
1.14 markus 600: /* This is called after receiving CHANNEL_CLOSE/IEOF. */
1.1 deraadt 601:
1.25 markus 602: void
603: channel_input_close()
1.1 deraadt 604: {
1.25 markus 605: int channel;
1.1 deraadt 606:
1.25 markus 607: /* Get the channel number and verify it. */
608: channel = packet_get_int();
609: if (channel < 0 || channel >= channels_alloc ||
610: channels[channel].type == SSH_CHANNEL_FREE)
611: packet_disconnect("Received data for nonexistent channel %d.", channel);
612:
613: if (!compat13) {
614: /* proto version 1.5 overloads CLOSE with IEOF */
615: chan_rcvd_ieof(&channels[channel]);
616: return;
617: }
618: /* Send a confirmation that we have closed the channel and no more
619: data is coming for it. */
620: packet_start(SSH_MSG_CHANNEL_CLOSE_CONFIRMATION);
621: packet_put_int(channels[channel].remote_id);
622: packet_send();
623:
624: /* If the channel is in closed state, we have sent a close
625: request, and the other side will eventually respond with a
626: confirmation. Thus, we cannot free the channel here, because
627: then there would be no-one to receive the confirmation. The
628: channel gets freed when the confirmation arrives. */
629: if (channels[channel].type != SSH_CHANNEL_CLOSED) {
630: /* Not a closed channel - mark it as draining, which will
631: cause it to be freed later. */
632: buffer_consume(&channels[channel].input,
633: buffer_len(&channels[channel].input));
634: channels[channel].type = SSH_CHANNEL_OUTPUT_DRAINING;
635: }
1.1 deraadt 636: }
637:
1.14 markus 638: /* This is called after receiving CHANNEL_CLOSE_CONFIRMATION/OCLOSE. */
1.1 deraadt 639:
1.25 markus 640: void
641: channel_input_close_confirmation()
1.1 deraadt 642: {
1.25 markus 643: int channel;
1.1 deraadt 644:
1.25 markus 645: /* Get the channel number and verify it. */
646: channel = packet_get_int();
647: if (channel < 0 || channel >= channels_alloc)
648: packet_disconnect("Received close confirmation for out-of-range channel %d.",
649: channel);
650:
651: if (!compat13) {
652: /* proto version 1.5 overloads CLOSE_CONFIRMATION with OCLOSE */
653: chan_rcvd_oclose(&channels[channel]);
654: return;
655: }
656: if (channels[channel].type != SSH_CHANNEL_CLOSED)
657: packet_disconnect("Received close confirmation for non-closed channel %d (type %d).",
658: channel, channels[channel].type);
1.1 deraadt 659:
1.25 markus 660: /* Free the channel. */
661: channel_free(channel);
1.1 deraadt 662: }
663:
664: /* This is called after receiving CHANNEL_OPEN_CONFIRMATION. */
665:
1.25 markus 666: void
667: channel_input_open_confirmation()
1.1 deraadt 668: {
1.25 markus 669: int channel, remote_channel;
1.1 deraadt 670:
1.25 markus 671: /* Get the channel number and verify it. */
672: channel = packet_get_int();
673: if (channel < 0 || channel >= channels_alloc ||
674: channels[channel].type != SSH_CHANNEL_OPENING)
675: packet_disconnect("Received open confirmation for non-opening channel %d.",
676: channel);
677:
678: /* Get remote side's id for this channel. */
679: remote_channel = packet_get_int();
680:
681: /* Record the remote channel number and mark that the channel is
682: now open. */
683: channels[channel].remote_id = remote_channel;
684: channels[channel].type = SSH_CHANNEL_OPEN;
1.1 deraadt 685: }
686:
687: /* This is called after receiving CHANNEL_OPEN_FAILURE from the other side. */
688:
1.25 markus 689: void
690: channel_input_open_failure()
1.1 deraadt 691: {
1.25 markus 692: int channel;
693:
694: /* Get the channel number and verify it. */
695: channel = packet_get_int();
696: if (channel < 0 || channel >= channels_alloc ||
697: channels[channel].type != SSH_CHANNEL_OPENING)
698: packet_disconnect("Received open failure for non-opening channel %d.",
699: channel);
1.1 deraadt 700:
1.25 markus 701: /* Free the channel. This will also close the socket. */
702: channel_free(channel);
1.1 deraadt 703: }
704:
705: /* Stops listening for channels, and removes any unix domain sockets that
706: we might have. */
707:
1.25 markus 708: void
709: channel_stop_listening()
1.1 deraadt 710: {
1.25 markus 711: int i;
712: for (i = 0; i < channels_alloc; i++) {
713: switch (channels[i].type) {
714: case SSH_CHANNEL_AUTH_SOCKET:
715: close(channels[i].sock);
716: remove(channels[i].path);
717: channel_free(i);
718: break;
719: case SSH_CHANNEL_PORT_LISTENER:
720: case SSH_CHANNEL_X11_LISTENER:
721: close(channels[i].sock);
722: channel_free(i);
723: break;
724: default:
725: break;
726: }
1.1 deraadt 727: }
728: }
729:
730: /* Closes the sockets of all channels. This is used to close extra file
731: descriptors after a fork. */
732:
1.25 markus 733: void
734: channel_close_all()
1.1 deraadt 735: {
1.25 markus 736: int i;
737: for (i = 0; i < channels_alloc; i++) {
738: if (channels[i].type != SSH_CHANNEL_FREE)
739: close(channels[i].sock);
740: }
1.1 deraadt 741: }
742:
743: /* Returns the maximum file descriptor number used by the channels. */
744:
1.25 markus 745: int
746: channel_max_fd()
1.1 deraadt 747: {
1.25 markus 748: return channel_max_fd_value;
1.1 deraadt 749: }
750:
751: /* Returns true if any channel is still open. */
752:
1.25 markus 753: int
754: channel_still_open()
1.1 deraadt 755: {
1.25 markus 756: unsigned int i;
757: for (i = 0; i < channels_alloc; i++)
758: switch (channels[i].type) {
759: case SSH_CHANNEL_FREE:
760: case SSH_CHANNEL_X11_LISTENER:
761: case SSH_CHANNEL_PORT_LISTENER:
762: case SSH_CHANNEL_CLOSED:
763: case SSH_CHANNEL_AUTH_SOCKET:
764: continue;
765: case SSH_CHANNEL_OPENING:
766: case SSH_CHANNEL_OPEN:
767: case SSH_CHANNEL_X11_OPEN:
768: return 1;
769: case SSH_CHANNEL_INPUT_DRAINING:
770: case SSH_CHANNEL_OUTPUT_DRAINING:
771: if (!compat13)
772: fatal("cannot happen: OUT_DRAIN");
773: return 1;
774: default:
775: fatal("channel_still_open: bad channel type %d", channels[i].type);
776: /* NOTREACHED */
777: }
778: return 0;
1.1 deraadt 779: }
780:
781: /* Returns a message describing the currently open forwarded
782: connections, suitable for sending to the client. The message
783: contains crlf pairs for newlines. */
784:
1.25 markus 785: char *
786: channel_open_message()
1.1 deraadt 787: {
1.25 markus 788: Buffer buffer;
789: int i;
790: char buf[512], *cp;
791:
792: buffer_init(&buffer);
793: snprintf(buf, sizeof buf, "The following connections are open:\r\n");
1.1 deraadt 794: buffer_append(&buffer, buf, strlen(buf));
1.25 markus 795: for (i = 0; i < channels_alloc; i++) {
796: Channel *c = &channels[i];
797: switch (c->type) {
798: case SSH_CHANNEL_FREE:
799: case SSH_CHANNEL_X11_LISTENER:
800: case SSH_CHANNEL_PORT_LISTENER:
801: case SSH_CHANNEL_CLOSED:
802: case SSH_CHANNEL_AUTH_SOCKET:
803: continue;
804: case SSH_CHANNEL_OPENING:
805: case SSH_CHANNEL_OPEN:
806: case SSH_CHANNEL_X11_OPEN:
807: case SSH_CHANNEL_INPUT_DRAINING:
808: case SSH_CHANNEL_OUTPUT_DRAINING:
809: snprintf(buf, sizeof buf, " #%d %.300s (t%d r%d i%d o%d)\r\n",
810: c->self, c->remote_name,
811: c->type, c->remote_id, c->istate, c->ostate);
812: buffer_append(&buffer, buf, strlen(buf));
813: continue;
814: default:
815: fatal("channel_still_open: bad channel type %d", c->type);
816: /* NOTREACHED */
817: }
818: }
819: buffer_append(&buffer, "\0", 1);
820: cp = xstrdup(buffer_ptr(&buffer));
821: buffer_free(&buffer);
822: return cp;
1.1 deraadt 823: }
824:
825: /* Initiate forwarding of connections to local port "port" through the secure
826: channel to host:port from remote side. */
827:
1.25 markus 828: void
829: channel_request_local_forwarding(int port, const char *host,
830: int host_port)
831: {
832: int ch, sock;
833: struct sockaddr_in sin;
834: extern Options options;
835:
836: if (strlen(host) > sizeof(channels[0].path) - 1)
837: packet_disconnect("Forward host name too long.");
838:
839: /* Create a port to listen for the host. */
840: sock = socket(AF_INET, SOCK_STREAM, 0);
841: if (sock < 0)
842: packet_disconnect("socket: %.100s", strerror(errno));
843:
844: /* Initialize socket address. */
845: memset(&sin, 0, sizeof(sin));
846: sin.sin_family = AF_INET;
847: if (options.gateway_ports == 1)
848: sin.sin_addr.s_addr = htonl(INADDR_ANY);
849: else
850: sin.sin_addr.s_addr = htonl(INADDR_LOOPBACK);
851: sin.sin_port = htons(port);
852:
853: /* Bind the socket to the address. */
854: if (bind(sock, (struct sockaddr *) & sin, sizeof(sin)) < 0)
855: packet_disconnect("bind: %.100s", strerror(errno));
856:
857: /* Start listening for connections on the socket. */
858: if (listen(sock, 5) < 0)
859: packet_disconnect("listen: %.100s", strerror(errno));
860:
861: /* Allocate a channel number for the socket. */
862: ch = channel_allocate(SSH_CHANNEL_PORT_LISTENER, sock,
863: xstrdup("port listener"));
864: strcpy(channels[ch].path, host);
865: channels[ch].host_port = host_port;
866: channels[ch].listening_port = port;
867: }
1.1 deraadt 868:
869: /* Initiate forwarding of connections to port "port" on remote host through
870: the secure channel to host:port from local side. */
871:
1.25 markus 872: void
873: channel_request_remote_forwarding(int port, const char *host,
874: int remote_port)
875: {
876: int payload_len;
877: /* Record locally that connection to this host/port is permitted. */
878: if (num_permitted_opens >= SSH_MAX_FORWARDS_PER_DIRECTION)
879: fatal("channel_request_remote_forwarding: too many forwards");
880:
881: permitted_opens[num_permitted_opens].host = xstrdup(host);
882: permitted_opens[num_permitted_opens].port = remote_port;
883: num_permitted_opens++;
884:
885: /* Send the forward request to the remote side. */
886: packet_start(SSH_CMSG_PORT_FORWARD_REQUEST);
887: packet_put_int(port);
888: packet_put_string(host, strlen(host));
889: packet_put_int(remote_port);
890: packet_send();
891: packet_write_wait();
892:
893: /* Wait for response from the remote side. It will send a
894: disconnect message on failure, and we will never see it here. */
895: packet_read_expect(&payload_len, SSH_SMSG_SUCCESS);
1.1 deraadt 896: }
897:
898: /* This is called after receiving CHANNEL_FORWARDING_REQUEST. This initates
899: listening for the port, and sends back a success reply (or disconnect
1.25 markus 900: message if there was an error). This never returns if there was an
1.1 deraadt 901: error. */
902:
1.25 markus 903: void
904: channel_input_port_forward_request(int is_root)
1.1 deraadt 905: {
1.25 markus 906: int port, host_port;
907: char *hostname;
1.1 deraadt 908:
1.25 markus 909: /* Get arguments from the packet. */
910: port = packet_get_int();
911: hostname = packet_get_string(NULL);
912: host_port = packet_get_int();
913:
914: /* Port numbers are 16 bit quantities. */
915: if ((port & 0xffff) != port)
916: packet_disconnect("Requested forwarding of nonexistent port %d.", port);
917:
918: /* Check that an unprivileged user is not trying to forward a
919: privileged port. */
920: if (port < IPPORT_RESERVED && !is_root)
921: packet_disconnect("Requested forwarding of port %d but user is not root.",
922: port);
1.1 deraadt 923:
1.25 markus 924: /* Initiate forwarding. */
925: channel_request_local_forwarding(port, hostname, host_port);
926:
927: /* Free the argument string. */
928: xfree(hostname);
1.1 deraadt 929: }
930:
931: /* This is called after receiving PORT_OPEN message. This attempts to connect
932: to the given host:port, and sends back CHANNEL_OPEN_CONFIRMATION or
933: CHANNEL_OPEN_FAILURE. */
934:
1.25 markus 935: void
936: channel_input_port_open(int payload_len)
1.1 deraadt 937: {
1.25 markus 938: int remote_channel, sock, newch, host_port, i;
939: struct sockaddr_in sin;
940: char *host, *originator_string;
941: struct hostent *hp;
942: int host_len, originator_len;
943:
944: /* Get remote channel number. */
945: remote_channel = packet_get_int();
946:
947: /* Get host name to connect to. */
948: host = packet_get_string(&host_len);
949:
950: /* Get port to connect to. */
951: host_port = packet_get_int();
952:
953: /* Get remote originator name. */
954: if (have_hostname_in_open)
955: originator_string = packet_get_string(&originator_len);
956: else
957: originator_string = xstrdup("unknown (remote did not supply name)");
958:
959: packet_integrity_check(payload_len,
960: 4 + 4 + host_len + 4 + 4 + originator_len,
961: SSH_MSG_PORT_OPEN);
962:
963: /* Check if opening that port is permitted. */
964: if (!all_opens_permitted) {
965: /* Go trough all permitted ports. */
966: for (i = 0; i < num_permitted_opens; i++)
967: if (permitted_opens[i].port == host_port &&
968: strcmp(permitted_opens[i].host, host) == 0)
969: break;
970:
971: /* Check if we found the requested port among those permitted. */
972: if (i >= num_permitted_opens) {
973: /* The port is not permitted. */
974: log("Received request to connect to %.100s:%d, but the request was denied.",
975: host, host_port);
976: packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
977: packet_put_int(remote_channel);
978: packet_send();
979: }
980: }
981: memset(&sin, 0, sizeof(sin));
982: sin.sin_addr.s_addr = inet_addr(host);
983: if ((sin.sin_addr.s_addr & 0xffffffff) != 0xffffffff) {
984: /* It was a valid numeric host address. */
985: sin.sin_family = AF_INET;
986: } else {
987: /* Look up the host address from the name servers. */
988: hp = gethostbyname(host);
989: if (!hp) {
990: error("%.100s: unknown host.", host);
991: goto fail;
992: }
993: if (!hp->h_addr_list[0]) {
994: error("%.100s: host has no IP address.", host);
995: goto fail;
996: }
997: sin.sin_family = hp->h_addrtype;
998: memcpy(&sin.sin_addr, hp->h_addr_list[0],
999: sizeof(sin.sin_addr));
1000: }
1001: sin.sin_port = htons(host_port);
1002:
1003: /* Create the socket. */
1004: sock = socket(sin.sin_family, SOCK_STREAM, 0);
1005: if (sock < 0) {
1006: error("socket: %.100s", strerror(errno));
1007: goto fail;
1008: }
1009: /* Connect to the host/port. */
1010: if (connect(sock, (struct sockaddr *) & sin, sizeof(sin)) < 0) {
1011: error("connect %.100s:%d: %.100s", host, host_port,
1012: strerror(errno));
1013: close(sock);
1014: goto fail;
1015: }
1016: /* Successful connection. */
1017:
1018: /* Allocate a channel for this connection. */
1019: newch = channel_allocate(SSH_CHANNEL_OPEN, sock, originator_string);
1020: channels[newch].remote_id = remote_channel;
1021:
1022: /* Send a confirmation to the remote host. */
1023: packet_start(SSH_MSG_CHANNEL_OPEN_CONFIRMATION);
1024: packet_put_int(remote_channel);
1025: packet_put_int(newch);
1026: packet_send();
1027:
1028: /* Free the argument string. */
1029: xfree(host);
1030:
1031: return;
1032:
1033: fail:
1034: /* Free the argument string. */
1035: xfree(host);
1036:
1037: /* Send refusal to the remote host. */
1038: packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
1039: packet_put_int(remote_channel);
1040: packet_send();
1.1 deraadt 1041: }
1042:
1.25 markus 1043: /* Creates an internet domain socket for listening for X11 connections.
1.1 deraadt 1044: Returns a suitable value for the DISPLAY variable, or NULL if an error
1045: occurs. */
1046:
1.25 markus 1047: char *
1048: x11_create_display_inet(int screen_number)
1.1 deraadt 1049: {
1.25 markus 1050: extern ServerOptions options;
1051: int display_number, port, sock;
1052: struct sockaddr_in sin;
1053: char buf[512];
1054: char hostname[MAXHOSTNAMELEN];
1055:
1056: for (display_number = options.x11_display_offset;
1057: display_number < MAX_DISPLAYS;
1058: display_number++) {
1059: port = 6000 + display_number;
1060: memset(&sin, 0, sizeof(sin));
1061: sin.sin_family = AF_INET;
1062: sin.sin_addr.s_addr = htonl(INADDR_ANY);
1063: sin.sin_port = htons(port);
1064:
1065: sock = socket(AF_INET, SOCK_STREAM, 0);
1066: if (sock < 0) {
1067: error("socket: %.100s", strerror(errno));
1068: return NULL;
1069: }
1070: if (bind(sock, (struct sockaddr *) & sin, sizeof(sin)) < 0) {
1071: debug("bind port %d: %.100s", port, strerror(errno));
1072: shutdown(sock, SHUT_RDWR);
1073: close(sock);
1074: continue;
1075: }
1076: break;
1077: }
1078: if (display_number >= MAX_DISPLAYS) {
1079: error("Failed to allocate internet-domain X11 display socket.");
1080: return NULL;
1081: }
1082: /* Start listening for connections on the socket. */
1083: if (listen(sock, 5) < 0) {
1084: error("listen: %.100s", strerror(errno));
1085: shutdown(sock, SHUT_RDWR);
1086: close(sock);
1087: return NULL;
1088: }
1089: /* Set up a suitable value for the DISPLAY variable. */
1090: if (gethostname(hostname, sizeof(hostname)) < 0)
1091: fatal("gethostname: %.100s", strerror(errno));
1092: snprintf(buf, sizeof buf, "%.400s:%d.%d", hostname,
1093: display_number, screen_number);
1094:
1095: /* Allocate a channel for the socket. */
1096: (void) channel_allocate(SSH_CHANNEL_X11_LISTENER, sock,
1097: xstrdup("X11 inet listener"));
1.1 deraadt 1098:
1.25 markus 1099: /* Return a suitable value for the DISPLAY environment variable. */
1100: return xstrdup(buf);
1.1 deraadt 1101: }
1102:
1103: #ifndef X_UNIX_PATH
1104: #define X_UNIX_PATH "/tmp/.X11-unix/X"
1105: #endif
1106:
1107: static
1108: int
1109: connect_local_xsocket(unsigned dnr)
1110: {
1.25 markus 1111: static const char *const x_sockets[] = {
1112: X_UNIX_PATH "%u",
1113: "/var/X/.X11-unix/X" "%u",
1114: "/usr/spool/sockets/X11/" "%u",
1115: NULL
1116: };
1117: int sock;
1118: struct sockaddr_un addr;
1119: const char *const * path;
1120:
1121: for (path = x_sockets; *path; ++path) {
1122: sock = socket(AF_UNIX, SOCK_STREAM, 0);
1123: if (sock < 0)
1124: error("socket: %.100s", strerror(errno));
1125: memset(&addr, 0, sizeof(addr));
1126: addr.sun_family = AF_UNIX;
1127: snprintf(addr.sun_path, sizeof addr.sun_path, *path, dnr);
1128: if (connect(sock, (struct sockaddr *) & addr, sizeof(addr)) == 0)
1129: return sock;
1130: close(sock);
1131: }
1132: error("connect %.100s: %.100s", addr.sun_path, strerror(errno));
1133: return -1;
1.1 deraadt 1134: }
1135:
1136:
1137: /* This is called when SSH_SMSG_X11_OPEN is received. The packet contains
1138: the remote channel number. We should do whatever we want, and respond
1139: with either SSH_MSG_OPEN_CONFIRMATION or SSH_MSG_OPEN_FAILURE. */
1140:
1.25 markus 1141: void
1142: x11_input_open(int payload_len)
1.1 deraadt 1143: {
1.25 markus 1144: int remote_channel, display_number, sock, newch;
1145: const char *display;
1146: struct sockaddr_in sin;
1147: char buf[1024], *cp, *remote_host;
1148: struct hostent *hp;
1149: int remote_len;
1150:
1151: /* Get remote channel number. */
1152: remote_channel = packet_get_int();
1153:
1154: /* Get remote originator name. */
1155: if (have_hostname_in_open)
1156: remote_host = packet_get_string(&remote_len);
1157: else
1158: remote_host = xstrdup("unknown (remote did not supply name)");
1159:
1160: debug("Received X11 open request.");
1161: packet_integrity_check(payload_len, 4 + 4 + remote_len, SSH_SMSG_X11_OPEN);
1162:
1163: /* Try to open a socket for the local X server. */
1164: display = getenv("DISPLAY");
1165: if (!display) {
1166: error("DISPLAY not set.");
1167: goto fail;
1168: }
1169: /* Now we decode the value of the DISPLAY variable and make a
1170: connection to the real X server. */
1171:
1172: /* Check if it is a unix domain socket. Unix domain displays are
1173: in one of the following formats: unix:d[.s], :d[.s], ::d[.s] */
1174: if (strncmp(display, "unix:", 5) == 0 ||
1175: display[0] == ':') {
1176: /* Connect to the unix domain socket. */
1177: if (sscanf(strrchr(display, ':') + 1, "%d", &display_number) != 1) {
1178: error("Could not parse display number from DISPLAY: %.100s",
1179: display);
1180: goto fail;
1181: }
1182: /* Create a socket. */
1183: sock = connect_local_xsocket(display_number);
1184: if (sock < 0)
1185: goto fail;
1186:
1187: /* OK, we now have a connection to the display. */
1188: goto success;
1189: }
1190: /* Connect to an inet socket. The DISPLAY value is supposedly
1191: hostname:d[.s], where hostname may also be numeric IP address. */
1192: strncpy(buf, display, sizeof(buf));
1193: buf[sizeof(buf) - 1] = 0;
1194: cp = strchr(buf, ':');
1195: if (!cp) {
1196: error("Could not find ':' in DISPLAY: %.100s", display);
1197: goto fail;
1198: }
1199: *cp = 0;
1200: /* buf now contains the host name. But first we parse the display
1201: number. */
1202: if (sscanf(cp + 1, "%d", &display_number) != 1) {
1203: error("Could not parse display number from DISPLAY: %.100s",
1204: display);
1205: goto fail;
1206: }
1207: /* Try to parse the host name as a numeric IP address. */
1208: memset(&sin, 0, sizeof(sin));
1209: sin.sin_addr.s_addr = inet_addr(buf);
1210: if ((sin.sin_addr.s_addr & 0xffffffff) != 0xffffffff) {
1211: /* It was a valid numeric host address. */
1212: sin.sin_family = AF_INET;
1213: } else {
1214: /* Not a numeric IP address. */
1215: /* Look up the host address from the name servers. */
1216: hp = gethostbyname(buf);
1217: if (!hp) {
1218: error("%.100s: unknown host.", buf);
1219: goto fail;
1220: }
1221: if (!hp->h_addr_list[0]) {
1222: error("%.100s: host has no IP address.", buf);
1223: goto fail;
1224: }
1225: sin.sin_family = hp->h_addrtype;
1226: memcpy(&sin.sin_addr, hp->h_addr_list[0],
1227: sizeof(sin.sin_addr));
1228: }
1229: /* Set port number. */
1230: sin.sin_port = htons(6000 + display_number);
1231:
1232: /* Create a socket. */
1233: sock = socket(sin.sin_family, SOCK_STREAM, 0);
1234: if (sock < 0) {
1235: error("socket: %.100s", strerror(errno));
1236: goto fail;
1237: }
1238: /* Connect it to the display. */
1239: if (connect(sock, (struct sockaddr *) & sin, sizeof(sin)) < 0) {
1240: error("connect %.100s:%d: %.100s", buf, 6000 + display_number,
1241: strerror(errno));
1242: close(sock);
1243: goto fail;
1244: }
1245: success:
1246: /* We have successfully obtained a connection to the real X display. */
1247:
1248: /* Allocate a channel for this connection. */
1249: if (x11_saved_proto == NULL)
1250: newch = channel_allocate(SSH_CHANNEL_OPEN, sock, remote_host);
1251: else
1252: newch = channel_allocate(SSH_CHANNEL_X11_OPEN, sock, remote_host);
1253: channels[newch].remote_id = remote_channel;
1254:
1255: /* Send a confirmation to the remote host. */
1256: packet_start(SSH_MSG_CHANNEL_OPEN_CONFIRMATION);
1257: packet_put_int(remote_channel);
1258: packet_put_int(newch);
1259: packet_send();
1260:
1261: return;
1262:
1263: fail:
1264: /* Send refusal to the remote host. */
1265: packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
1266: packet_put_int(remote_channel);
1267: packet_send();
1.1 deraadt 1268: }
1269:
1270: /* Requests forwarding of X11 connections, generates fake authentication
1271: data, and enables authentication spoofing. */
1272:
1.25 markus 1273: void
1274: x11_request_forwarding_with_spoofing(const char *proto, const char *data)
1.1 deraadt 1275: {
1.25 markus 1276: unsigned int data_len = (unsigned int) strlen(data) / 2;
1277: unsigned int i, value;
1278: char *new_data;
1279: int screen_number;
1280: const char *cp;
1281: u_int32_t rand = 0;
1282:
1283: cp = getenv("DISPLAY");
1284: if (cp)
1285: cp = strchr(cp, ':');
1286: if (cp)
1287: cp = strchr(cp, '.');
1288: if (cp)
1289: screen_number = atoi(cp + 1);
1290: else
1291: screen_number = 0;
1292:
1293: /* Save protocol name. */
1294: x11_saved_proto = xstrdup(proto);
1295:
1296: /* Extract real authentication data and generate fake data of the
1297: same length. */
1298: x11_saved_data = xmalloc(data_len);
1299: x11_fake_data = xmalloc(data_len);
1300: for (i = 0; i < data_len; i++) {
1301: if (sscanf(data + 2 * i, "%2x", &value) != 1)
1302: fatal("x11_request_forwarding: bad authentication data: %.100s", data);
1303: if (i % 4 == 0)
1304: rand = arc4random();
1305: x11_saved_data[i] = value;
1306: x11_fake_data[i] = rand & 0xff;
1307: rand >>= 8;
1308: }
1309: x11_saved_data_len = data_len;
1310: x11_fake_data_len = data_len;
1311:
1312: /* Convert the fake data into hex. */
1313: new_data = xmalloc(2 * data_len + 1);
1314: for (i = 0; i < data_len; i++)
1315: sprintf(new_data + 2 * i, "%02x", (unsigned char) x11_fake_data[i]);
1316:
1317: /* Send the request packet. */
1318: packet_start(SSH_CMSG_X11_REQUEST_FORWARDING);
1319: packet_put_string(proto, strlen(proto));
1320: packet_put_string(new_data, strlen(new_data));
1321: packet_put_int(screen_number);
1322: packet_send();
1323: packet_write_wait();
1324: xfree(new_data);
1.1 deraadt 1325: }
1326:
1327: /* Sends a message to the server to request authentication fd forwarding. */
1328:
1.25 markus 1329: void
1330: auth_request_forwarding()
1.1 deraadt 1331: {
1.25 markus 1332: packet_start(SSH_CMSG_AGENT_REQUEST_FORWARDING);
1333: packet_send();
1334: packet_write_wait();
1.1 deraadt 1335: }
1336:
1337: /* Returns the name of the forwarded authentication socket. Returns NULL
1338: if there is no forwarded authentication socket. The returned value
1339: points to a static buffer. */
1340:
1.25 markus 1341: char *
1342: auth_get_socket_name()
1.1 deraadt 1343: {
1.25 markus 1344: return channel_forwarded_auth_socket_name;
1.1 deraadt 1345: }
1346:
1.12 markus 1347: /* removes the agent forwarding socket */
1348:
1.25 markus 1349: void
1350: cleanup_socket(void)
1351: {
1352: remove(channel_forwarded_auth_socket_name);
1353: rmdir(channel_forwarded_auth_socket_dir);
1.12 markus 1354: }
1355:
1.1 deraadt 1356: /* This if called to process SSH_CMSG_AGENT_REQUEST_FORWARDING on the server.
1357: This starts forwarding authentication requests. */
1358:
1.25 markus 1359: void
1360: auth_input_request_forwarding(struct passwd * pw)
1.1 deraadt 1361: {
1.25 markus 1362: int sock, newch;
1363: struct sockaddr_un sunaddr;
1364:
1365: if (auth_get_socket_name() != NULL)
1366: fatal("Protocol error: authentication forwarding requested twice.");
1367:
1368: /* Temporarily drop privileged uid for mkdir/bind. */
1369: temporarily_use_uid(pw->pw_uid);
1370:
1371: /* Allocate a buffer for the socket name, and format the name. */
1372: channel_forwarded_auth_socket_name = xmalloc(MAX_SOCKET_NAME);
1373: channel_forwarded_auth_socket_dir = xmalloc(MAX_SOCKET_NAME);
1374: strlcpy(channel_forwarded_auth_socket_dir, "/tmp/ssh-XXXXXXXX", MAX_SOCKET_NAME);
1375:
1376: /* Create private directory for socket */
1377: if (mkdtemp(channel_forwarded_auth_socket_dir) == NULL)
1378: packet_disconnect("mkdtemp: %.100s", strerror(errno));
1379: snprintf(channel_forwarded_auth_socket_name, MAX_SOCKET_NAME, "%s/agent.%d",
1380: channel_forwarded_auth_socket_dir, (int) getpid());
1381:
1382: if (atexit(cleanup_socket) < 0) {
1383: int saved = errno;
1384: cleanup_socket();
1385: packet_disconnect("socket: %.100s", strerror(saved));
1386: }
1387: /* Create the socket. */
1388: sock = socket(AF_UNIX, SOCK_STREAM, 0);
1389: if (sock < 0)
1390: packet_disconnect("socket: %.100s", strerror(errno));
1391:
1392: /* Bind it to the name. */
1393: memset(&sunaddr, 0, sizeof(sunaddr));
1394: sunaddr.sun_family = AF_UNIX;
1395: strncpy(sunaddr.sun_path, channel_forwarded_auth_socket_name,
1396: sizeof(sunaddr.sun_path));
1397:
1398: if (bind(sock, (struct sockaddr *) & sunaddr, sizeof(sunaddr)) < 0)
1399: packet_disconnect("bind: %.100s", strerror(errno));
1400:
1401: /* Restore the privileged uid. */
1402: restore_uid();
1403:
1404: /* Start listening on the socket. */
1405: if (listen(sock, 5) < 0)
1406: packet_disconnect("listen: %.100s", strerror(errno));
1407:
1408: /* Allocate a channel for the authentication agent socket. */
1409: newch = channel_allocate(SSH_CHANNEL_AUTH_SOCKET, sock,
1410: xstrdup("auth socket"));
1411: strcpy(channels[newch].path, channel_forwarded_auth_socket_name);
1.1 deraadt 1412: }
1413:
1414: /* This is called to process an SSH_SMSG_AGENT_OPEN message. */
1415:
1.25 markus 1416: void
1417: auth_input_open_request()
1.1 deraadt 1418: {
1.25 markus 1419: int remch, sock, newch;
1420: char *dummyname;
1421:
1422: /* Read the remote channel number from the message. */
1423: remch = packet_get_int();
1424:
1425: /* Get a connection to the local authentication agent (this may
1426: again get forwarded). */
1427: sock = ssh_get_authentication_socket();
1428:
1429: /* If we could not connect the agent, send an error message back
1430: to the server. This should never happen unless the agent dies,
1431: because authentication forwarding is only enabled if we have an
1432: agent. */
1433: if (sock < 0) {
1434: packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
1435: packet_put_int(remch);
1436: packet_send();
1437: return;
1438: }
1439: debug("Forwarding authentication connection.");
1.1 deraadt 1440:
1.25 markus 1441: /* Dummy host name. This will be freed when the channel is freed;
1442: it will still be valid in the packet_put_string below since the
1443: channel cannot yet be freed at that point. */
1444: dummyname = xstrdup("authentication agent connection");
1445:
1446: newch = channel_allocate(SSH_CHANNEL_OPEN, sock, dummyname);
1447: channels[newch].remote_id = remch;
1448:
1449: /* Send a confirmation to the remote host. */
1450: packet_start(SSH_MSG_CHANNEL_OPEN_CONFIRMATION);
1451: packet_put_int(remch);
1452: packet_put_int(newch);
1453: packet_send();
1.1 deraadt 1454: }
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